ZWO EAF on Takahashi TOA-150?

N Foldager:
Thank you very much for your answers. I'll go for it and see what happens.

I wonder if it would be a good idea to couple the EAF to the fine adjustment shaft?   Then I would get finer regulation and lower leverage for heavy stuff. 

Best regards,
Niels

Ashraf AbuSara:
tilt or focus drift?

Nick Grundy:

Ashraf AbuSara:
tilt or focus drift?

If I remember correctly, the EAF on the stock focuser was ok (no focus drift), but there was definitely the light leak. (tested with a flashlight doing darks). I think you can print a bracket though from thingiverse or printables

Nick Grundy:

James Peirce:
What light leak?

on my Epsilon 160 stock focuser, there was a light leak. As far as I could tell, it was from the within the focuser tube. This is the attachment someone else pointed to. Apparently it fits just in front of the corrector? I printed one but didn't get it to fit perfect. I ended up getting the Leo anyways though so I stopped trying. 

James Peirce:

Ashraf AbuSara:

James Peirce:
Does it have the 8mm shaft attachment point most of the other Takahashi focusers have? In which case, you can install the ZWO EAF using stock parts along with a suitable 5mm to 8mm coupling. Those can be purchased on Amazon and all are just products available from AliExpress, etc. with markup added. You can also easily get the coupling of the style ZWO includes.

I wrote a little thing about my FS-60 a while back and have since put them on other Takahashis like the Epsilon 180D.

https://www.cloudynights.com/topic/825048-attach-zwo-eaf-to-takahashi-fs-60cbq-fc-76dcu-etc/

ZWO sells an accessory pack for Takahashi and other telescopes that includes an alternative mounting rail. But the bar-shaped one that comes with the EAF ought to have plenty of clearance on that refractor.

One thing that strikes me is that you may want to get a compression fit coupling instead of one which bites into the shaft, depending on how heavy the optical train will be. But I haven’t had issues with an APS-C camera, filter wheel, etc.

Excellent post. You are one of the few Epsilon owners here that I didn't see using an Optec Leo Focuser. I actually have a leo focuser myself, but frankly I would just prefer to use the EAF if that works. I like to use an OAG and it might be difficult to do with the native corrector and the Leo focuser. Have you noticed any issues with it in terms of tilt or focus drift?

Thanks! Regarding the Optec Leo Focuser, I imagine I would use one if this was set up in an observatory. As it stands, I do all of my imaging on the road, so I like to keep things pretty simple and compact wherever I can. I have a couple cameras which are tilt adjusted and mount to my telescopes using the Baader QuickChanger system, which, while manual, gives me a point of rotation that does not tilt and serves me well enough. So it was reasonable to simply set the Takahashi CAA to my preferred orientation and leave it there.

Based on my limited experience with only two relatively young Epsilons, rotating the stock CAA does not introduce material tilt or collimation issues. I suspect part of this is that some people make changes and do not follow the full collimation routine for the telescope, which involves rotating the CAA, and collimates the telescope not just for one point of rotation but across the range of rotation. And because my cameras are individually tilt adjusted to the point of attachment, this also means I have not had to deal with mechanical tilt from the Takahashi focuser parts themselves. Maybe copy variation exists or perhaps there have been design improvements.

Focus drift has not been an issue for me using the ZWO EAF, nor with this focuser. I have the tension adjusted to a rather weak point so the EAF is probably taking on some tension to hold the focuser in place. I guess if I had a rather heavy optical train and it seemed to shift a bit, I might try tensioning the focuser a little bit more. But I haven’t had to solve that potential problem yet.

- - -

A couple addenda:

A new M4 bolt is needed and probably won’t match anything that comes with the ZWO EAF. Like the 8mm shaft, the relatively young Takahashis I have used all use that same M4 attachment under the focuser. I used my digital calipers to measure the length of the thread of the stock two-point head that comes with the stock focuser and added the depth of the mounting rail. Probably goes without saying that one can usually be purchased at a big box home improvement store or ground down from the odds and ends we all probably have. I have a multi-part kit of stainless steel socket head M[x] bolts I can just grab from.

The Takahashi and other telescopes accessory pack ZWO sells does come with a 5mm to 8mm coupler that works for these telescopes. Just feels like an unnecessarily expensive solution unless the alternative bracket is desired for some reason.

In my photo example I used a more rigid compression-fit coupling that is fatter. Works great, and I like it more than the style that comes with the EAF that bites the shaft with grub screws. Since it is less rigid, although still flexible, I set it up with more care to minimize flex, and I used a couple washers to space out the bracket that came with the EAF so it has enough clearance to spin without rubbing.

Ashraf AbuSara:

N Foldager:
The focuser on my TOA-150 has a coarse and a fine (1:8) knob. (The latter refitted, Takahashi.)

I wonder if I can fit a ZWO EAF for the fine adjustment?

That would reduce the load on the EAF to 1/8, but increase the travel time 8x.

Those of you with experience for EAF:
Would that solution be feasible?
Would it for example be too slow to work with or give other problems?
Or a great idea?
What do you think?

Best regards,
Niels

In general it is not advisable to put the EAF on any fine knob focuser. Not just due to travel time but I think the fine focuser knob is much more likely to get damaged from excessive torque if lets say you reach the end of the focuser with your EAF and you have not set the limits correctly. Also there is not much reason to do so the steps in the EAF are fine enough for focusing on the coarse focusing knob.

Bill McLaughlin:
I decided not to wait since they estimate my 160 in about 3 months so I will use either a LEO or the new Hercules but I figured the information might be of interest.